But she also makes regular trips to the surrounding countryside. One sunny spring afternoon, Tian toured the family farm of Gao Shengdian, a longtime farmer who, together with his wife, grows wheat, rice, corn, and 10 kinds of vegetables.

Like most farmers in China, Mr. Gao once used large quantities of chemical fertilizer. He purchased this fertilizer from the wheelbarrow of an unlicensed local vendor and he believes it was often impure, even toxic.

Now Gao points proudly to a series of tidy tomato plots. They are labeled with new signs that read, in neatly written Chinese characters, "Green vegetable farmland." He is converting these plots to organic farming, a three-year process. For Tian and other residents downstream, this means less agricultural pollution in their water supply.

This farm is one of a dozen now enrolled in a sustainable-­agriculture program that Tian helped launch three years ago. An environmental group that she heads splits the cost of equipment to produce "biofertilizer" from compost and manure on the farms, provides tips on what crops grow best, and connects farmers with nearby urban consumers who want organically grown produce.

Many more families have requested to join the program. Gao says his neighbors are jealous.

But Tian is growing the initiative slowly, taking time to perfect the model. "When I think about how to make a project sustainable, I don't just think about the land," she says. "The human relationships must be sustainable, too. We need to figure out how to make everyone's interests meet."

Tian didn't set out to save the countryside. She first embarked to clean up the city. But, as she found, those two goals are intertwined.

Her hometown of Chengdu is an ancient city at the convergence of the Fu and Nan rivers in southwest China. Like many Chinese cities, it began to grow rapidly in the 1970s. Factories began to dump wastewater into the rivers. Several thousand food vendors and small shopkeepers did the same. Sewage pipes led directly into urban canals.

At the time, Tian was working as a journalist. There was little precedent for environmental cleanup in China, but through her work she learned about international discussions on the environment, including the 1992 United Nations' "Earth Summit" in Rio de Janeiro, which made "sustainable development" a global buzzword.

In the early 1990s, Tian began to lobby the city government to clean up the rivers. She helped convince local authorities that a cleaner environment would improve the city's image with foreign investors and tourists, and they hired her to establish a fledgling conservation office. In the next decade, she says the city spent about 10 billion yuan ($1.4 billion), on river cleanup.

Today many factories have moved outside Chengdu city limits. Local air and water quality have improved. The rivers are no longer brown. The United Nations Environment Program in 2000 recognized Chengdu at a conference on “Learning From Best Practices.” The city has even built parkland and planted cherry trees along sections of the rivers.Tian worries about the potential for backsliding if public attention doesn’t remain focused on these issues. In 2003, she founded an environmental nonprofit, Chengdu Urban Rivers Association and began to work with local university students on a “Get More Green” outreach campaign. “If we don’t have good environmental education after we improve the rivers,” she says, “our progress could disappear.”

Fertilizer overuse hurts riversRecently, Tian has turned her attention to another problem. Tests revealed that 60 percent of the remaining pollution in the rivers, which are still not fit for drinking or swimming, comes from the heavy usage of fertilizers and pesticides on farmland upstream.

Three years ago, Tian began to visit farmers in the surrounding countryside. Her purpose was to gather information. “I knew nothing would change if I just said, ‘Do this.’ I had to figure out what they needed, so we could work together.”

Gao’s situation was typical. His family is Buddhist, so he tries to respect natural balance. “I would rather not put all those chemicals in the ground,” he says, “but I must make a living somehow.” He also had a more worldly complaint: He knew he was being overcharged by the fertilizer vendor, who sold him adulterated goods, and by the businessman who bought his crops to sell to supermarkets at high margins.“But what choice did I have?” Gao wondered. Many farmers had similar frustrations.

Tian designed a program to address many concerns at once, with financial support from city ministries and the World Wildlife Fund China. The farmers needed some kind of fertilizer to keep their yields relatively high, so she equipped them to make their own. They also needed a way to reach customers, so she connected them directly with a small network of health-conscious consumers in Chengdu. They needed information and support, which her group provides on its regular visits.This time, Tian asks, “Is there anything else you need?”

Tian hopes to eventually expand the program, with further financial support from the government and international nongovernmental organizations.

Better methods help certification

This is not the only sustainable-agriculture project in China. Outside Beijing, a husband and wife in 2002 started their own organic farm, “Lovely Green Cow,” and sell produce directly to a health-conscious Beijing restaurant. In Yunnan Province, a Chinese nonprofit, Global Environmental Institute, operates a similar biofertilizer program. The central environment ministry has also established its own Organic Food Development Center.

Observers wonder to what extent such programs can grow, and how they may one day affect consumers in China and abroad. According to the World Trade Organization, China is the world’s largest food exporter.“The Chinese government understands it needs to shift to higher-value and safer goods,” says Linden Ellis of the China Environment Forum at the Woodrow Wilson Center in Washington. However, she adds, there is often a gap between intentions and implementation.

However, he thinks the situation can be improved if new incentives are introduced. For example, he believes the US Food and Drug Administration should enact “more stringent requirements on importers to work directly with their suppliers to ensure product safety.”

In a country where regulatory enforcement is weak, the crux of Tian’s philosophy is finding common interests. She is starting small, but her philosophy is scalable.

For his part, Gao hopes to one day open an organic and Buddhist restaurant for villagers and day-trippers from Chengdu. “So many people leave the countryside for the city,” he says. “There should be ways to bring people back to the countryside.”

Tian smiled. She knew he was talking about someone in particular. His son left the village to find work many years ago, but says he may return home if business is good.